The present invention relates generally to electric machines and more particularly to a sensorless electric machine, a component thereof, vehicles that employ the component and electric machine, and methods of making and operating the same.
With an electric machine, be it an interior permanent magnet (IPM) machine, permanent magnet (PM) assisted synchronous reluctance machine (SRM), or an SRM, position is a critical informational element for torque control at and near zero excitation frequency. Typically, an encoder, tachometer, or resolver is used with electric machines as the position sensor.
However, the position sensor (e.g., encoder) along with its cabling and interface electronics contributes a significant portion of the motor drive system cost and overall complexity and is often a major reliability concern. Since the advent of the high frequency injection method for zero frequency encoderless control, encoderless controls have seen great improvements but none have found success in recovering the full, or near full, torque capability of the machine. This is due to loss of small signal saliency at high-load levels for the machine.
Accordingly, there is an ongoing need for improvement of current electric machine technologies that address complexity, cost, efficiency, and/or performance.